There is a great site that has a variety of hi res multichannel lossless master samples, mostly classical. These are the production originals used for SACDs and Bluray, many in the raw DXD format.

I particularly like: "Bridge Over Troubled Water (Simon & Garfunkel) Iver Kleive (church organ)". It's starts out very soft and just gets louder and more powerful as it goes, it scared me the first time I heard it